1. Field of the Invention
The present invention relates generally to data processing methods and devices. More particularly, the present invention relates to use of a multiplexer for external computer access to an internal data modem associated with a host computer.
2. Discussion of Related Art
In next generation information systems for vehicles such as automobiles, it is desirable to provide functionality and flexibility for operator convenience and safety. Typical systems will include a host computer to monitor vehicle events including emergency conditions such as air bag deployment or flat tires and provide an indication to an operator of the vehicle. In addition, in a vehicle equipped with a telecommunication device such as a cellular telephone, an emergency communication may be sent to a service provider to provide an alert about an emergency situation for the vehicle. Further, the vehicle may be equipped with a global positioning system (GPS) unit for geographic positioning of the vehicle. Calls may be made to the service provider for directions or other information using position information from the GPS unit.
Another level of operator convenience is provided by including a connection for a detachable computer in the vehicle. For example, a standard connector is provided in the dash or console or other convenient location in the passenger cabin of the vehicle. The operator or a passenger may connect an external computer, such as a laptop computer, to the connector. The connector may in turn be electrically coupled with a cellular telephone to provide remote access for the external computer. In this manner, the system provides access to electronic mail, the internet and other data sources, either directly or through the service provider. Such next generation vehicles will feature multiple communicators accessing a limited number of telecommunication devices.
However, there is a possibility for a conflict between a communication made from the external computer and a host processor which monitors vehicle events. If an emergency communication from the host processor must be made while the external computer is engaged with the cellular telephone, an arbitration between the preexisting communication and the emergency communication must be made. This may be done in the software controlling the host processor and external computer, but that may conflict with other operations of those devices. Further, not all external computers run identical systems so a software solution may not be applicable to all devices externally attached to the system.
Accordingly, there is a need for a method and apparatus for prioritizing access to the telecommunication device among multiple communicators in a vehicle.